rxdb

db.heroes
  .find()
  .sort('name')
  .$ // <- returns observable of query
  .subscribe( docs => {
    myDomElement.innerHTML = docs
      .map(doc => '<li>' + doc.name + '</li>')
      .join();
  });

Use-Case-Example

Imagine you have a very big collection with many user-documents. At your page you want to display a toplist with users which have the most points and are currently logged in.
You create a query and subscribe to it.

const query = usersCollection.find().where('loggedIn').eq(true).sort('points');
query.$.subscribe(users => {
    document.querySelector('body').innerHTML = users
        .reduce((prev, cur) => prev + cur.username+ '<br/>', '');
});

As you may detect, the query can take very long time to run, because you have thousands of users in the collection.
When a user now logs off, the whole query will re-run over the database which takes again very long.

await anyUser.incrementalPatch({loggedIn: false});

But not with the EventReduce.
Now, when one user logs off, it will calculate the new results from the current results plus the RxChangeEvent. This often can be done in-memory without making IO-requests to the storage-engine. EventReduce not only works on subscribed queries, but also when you do multiple .exec()'s on the same query.

const mySchema = {
    title: "hero schema",
    version: 0,                 // <- incremental version-number
    description: "describes a simple hero",
    primaryKey: 'name',         // <- 'name' is the primary key for the collection, it must be unique, required and of the type string 
    type: "object",
    properties: {
        name: {
            type: "string",
            maxLength: 30
        },
        secret: {
            type: "string",
        },
        skills: {
            type: "array",
            maxItems: 5,
            uniqueItems: true,
            item: {
                type: "object",
                properties: {
                    name: {
                        type: "string"
                    },
                    damage: {
                        type: "number"
                    }
                }
            }
        }
    },
    required: ["color"],
    encrypted: ["secret"] // <- this means that the value of this field is stored encrypted
};

// normal query
myCollection.find({
  selector: {
    name: {
      $ne: 'Alice'
    },
    age: {
      $gt: 67
    }
  },
  sort: [{ age: 'desc' }],
  limit: 10
})

// chained query
myCollection
  .find()
  .where('name').ne('Alice')
  .where('age').gt(18).lt(67)
  .limit(10)
  .sort('-age')
  .exec().then( docs => {
    console.dir(docs);
  });

{
  "title": "my schema",
  "properties": {
    "secret": {
      "type": "string",
      "encrypted": true
    }
  },
  "encrypted": [
    "secret"
  ]
}

// export a single collection
const jsonCol = await myCollection.dump();

// export the whole database
const jsonDB = await myDatabase.dump();

// import the dump to the collection
await emptyCollection.importDump(json);


// import the dump to the database
await emptyDatabase.importDump(json);

Example:

// when you save an object with big keys
await myCollection.insert({
  firstName: 'foo'
  lastName:  'bar'
  stupidLongKey: 5
});

// key compression will internally transform it to
{
  '|a': 'foo'
  '|b':  'bar'
  '|c': 5
}

// so instead of 46 chars, the compressed-version has only 28
// the compression works internally, so you can of course still access values via the original key.names and run normal queries.
console.log(myDoc.firstName);
// 'foo'